Lib/idlelib/SearchEngine.py

'''Define SearchEngine for search dialogs.'''
import re
from Tkinter import *
import tkMessageBox

def get(root):
    '''Return the singleton SearchEngine instance for the process.

    The single SearchEngine saves settings between dialog instances.
    If there is not a SearchEngine already, make one.
    '''
    if not hasattr(root, "_searchengine"):
        root._searchengine = SearchEngine(root)
        # This creates a cycle that persists until root is deleted.
    return root._searchengine

class SearchEngine:
    """Handles searching a text widget for Find, Replace, and Grep."""

    def __init__(self, root):
        '''Initialize Variables that save search state.

        The dialogs bind these to the UI elements present in the dialogs.
        '''
        self.root = root
        self.patvar = StringVar(root)           # search pattern
        self.revar = BooleanVar(root)           # regular expression?
        self.casevar = BooleanVar(root)         # match case?
        self.wordvar = BooleanVar(root)         # match whole word?
        self.wrapvar = BooleanVar(root)         # wrap around buffer?
        self.wrapvar.set(1)                     # (on by default)
        self.backvar = BooleanVar(root)         # search backwards?

    # Access methods

    def getpat(self):
        return self.patvar.get()

    def setpat(self, pat):
        self.patvar.set(pat)

    def isre(self):
        return self.revar.get()

    def iscase(self):
        return self.casevar.get()

    def isword(self):
        return self.wordvar.get()

    def iswrap(self):
        return self.wrapvar.get()

    def isback(self):
        return self.backvar.get()

    # Higher level access methods

    def getcookedpat(self):
        pat = self.getpat()
        if not self.isre():
            pat = re.escape(pat)
        if self.isword():
            pat = r"\b%s\b" % pat
        return pat

    def getprog(self):
        "Return compiled cooked search pattern."
        pat = self.getpat()
        if not pat:
            self.report_error(pat, "Empty regular expression")
            return None
        pat = self.getcookedpat()
        flags = 0
        if not self.iscase():
            flags = flags | re.IGNORECASE
        try:
            prog = re.compile(pat, flags)
        except re.error as what:
            try:
                msg, col = what
            except:
                msg = str(what)
                col = -1
            self.report_error(pat, msg, col)
            return None
        return prog

    def report_error(self, pat, msg, col=-1):
        # Derived class could override this with something fancier
        msg = "Error: " + str(msg)
        if pat:
            msg = msg + "\np\Pattern: " + str(pat)
        if col >= 0:
            msg = msg + "\nOffset: " + str(col)
        tkMessageBox.showerror("Regular expression error",
                               msg, master=self.root)

    def setcookedpat(self, pat):
        if self.isre():
            pat = re.escape(pat)
        self.setpat(pat)

    def search_text(self, text, prog=None, ok=0):
        '''Return (lineno, matchobj) for prog in text widget, or None.

        If prog is given, it should be a precompiled pattern.
        Wrap (yes/no) and direction (forward/back) settings are used.

        The search starts at the selection (if there is one) or at the
        insert mark (otherwise).  If the search is forward, it starts
        at the right of the selection; for a backward search, it
        starts at the left end.  An empty match exactly at either end
        of the selection (or at the insert mark if there is no
        selection) is ignored  unless the ok flag is true -- this is
        done to guarantee progress.

        If the search is allowed to wrap around, it will return the
        original selection if (and only if) it is the only match.
        '''

        if not prog:
            prog = self.getprog()
            if not prog:
                return None # Compilation failed -- stop
        wrap = self.wrapvar.get()
        first, last = get_selection(text)
        if self.isback():
            if ok:
                start = last
            else:
                start = first
            line, col = get_line_col(start)
            res = self.search_backward(text, prog, line, col, wrap, ok)
        else:
            if ok:
                start = first
            else:
                start = last
            line, col = get_line_col(start)
            res = self.search_forward(text, prog, line, col, wrap, ok)
        return res

    def search_forward(self, text, prog, line, col, wrap, ok=0):
        wrapped = 0
        startline = line
        chars = text.get("%d.0" % line, "%d.0" % (line+1))
        while chars:
            m = prog.search(chars[:-1], col)
            if m:
                if ok or m.end() > col:
                    return line, m
            line = line + 1
            if wrapped and line > startline:
                break
            col = 0
            ok = 1
            chars = text.get("%d.0" % line, "%d.0" % (line+1))
            if not chars and wrap:
                wrapped = 1
                wrap = 0
                line = 1
                chars = text.get("1.0", "2.0")
        return None

    def search_backward(self, text, prog, line, col, wrap, ok=0):
        wrapped = 0
        startline = line
        chars = text.get("%d.0" % line, "%d.0" % (line+1))
        while 1:
            m = search_reverse(prog, chars[:-1], col)
            if m:
                if ok or m.start() < col:
                    return line, m
            line = line - 1
            if wrapped and line < startline:
                break
            ok = 1
            if line <= 0:
                if not wrap:
                    break
                wrapped = 1
                wrap = 0
                pos = text.index("end-1c")
                line, col = map(int, pos.split("."))
            chars = text.get("%d.0" % line, "%d.0" % (line+1))
            col = len(chars) - 1
        return None

def search_reverse(prog, chars, col):
    '''Search backwards in a string (line of text).

    This is done by searching forwards until there is no match.
    '''
    m = prog.search(chars)
    if not m:
        return None
    found = None
    i, j = m.span()
    while i < col and j <= col:
        found = m
        if i == j:
            j = j+1
        m = prog.search(chars, j)
        if not m:
            break
        i, j = m.span()
    return found

def get_selection(text):
    '''Return tuple of 'line.col' indexes from selection or insert mark.
    '''
    try:
        first = text.index("sel.first")
        last = text.index("sel.last")
    except TclError:
        first = last = None
    if not first:
        first = text.index("insert")
    if not last:
        last = first
    return first, last

def get_line_col(index):
    '''Return (line, col) tuple of ints from 'line.col' string.'''
    line, col = map(int, index.split(".")) # Fails on invalid index
    return line, col

##if __name__ == "__main__":
##    from test import support; support.use_resources = ['gui']
##    import unittest
##    unittest.main('idlelib.idle_test.test_searchengine', verbosity=2, exit=False)